Analytical and prospective evaluation of urinary cytokeratin 19 fragment in bladder cancer

We evaluated CYFRA 21-1, an immunoradiometric assay, developed to detect soluble cytokaratin 19 fragment, for its diagnostic performance in bladder transitional cell carcinoma as well as its analytical performance.

We assessed CYFRA 21-1 in the serum and urine of 182 patients, including 66 with bladder transitional cell carcinoma (group 1), 66 with another urological pathology (group 2) and 50 free of urothelial disease (group 3). The power of urinary CYFRA as a diagnostic test for bladder transitional cell carcinoma was evaluated by receiver operating characteristics curve analysis. Analytical performance was assessed by determining intra-assay and interassay precision, and accuracy by dilution testing and recovery of supplemented analyte.

Mean urinary CYFRA plus or minus standard deviation was 154.39+/-49.00, 22.6+/-8.9 and 2.40+/-0.14 ng./ml. in groups 1 to 3, respectively (significantly different). Receiver operating characteristics curve analysis revealed optimal 96.9% sensitivity and 67.2% specificity for a threshold value of 4 ng./ml. Analytical determination showed that intra-assay and interassay precision provides a satisfactory coefficient of variation. The assay for accuracy had acceptable recovery in diluted samples as well as in those with supplemented analyte.

The urinary immunoradiometric CYFRA 21-1 assay performs well analytically. Urinary CYFRA 21-1 is a useful marker for diagnosing transitional cell carcinoma and provides sensitivity in low grade disease.